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Reduced-folate carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart.

Maddox DM, Manlapat A, Roon P, Prasad P, Ganapathy V, Smith SB - BMC Dev. Biol. (2003)

Bottom Line: Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking.Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy.These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, USA. oxmandm@yahoo.com

ABSTRACT

Background: Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively.

Results: In the mouse, RFC transcripts and protein are expressed in the E10.0 placenta and yolk sac. In the E9.0 to E11.5 mouse embryo RFC is widely detectable, with intense signal localized to cell populations in the neural tube, craniofacial region, limb buds and heart. During early development, RFC is expressed throughout the eye, but by E12.5, RFC protein becomes localized to the retinal pigment epithelium (RPE).

Conclusions: Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy. The mechanism, however, by which folate supplementation ameliorates the occurrence of developmental defects is unclear. The present work demonstrates that RFC is present in placenta and yolk sac and provides the first evidence that it is expressed in the neural tube, craniofacial region, limb buds and heart during organogenesis. These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

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Immunofluorescent and immunohistochemical detection of RFC in developing mouse eye. Panel A demonstrates immunofluorescent signal for RFC present throughout the developing retina and lens of an E10.0 ICR mouse embryo. As development continues through E12.5, signal in the lens diminishes, while the signal in the retina becomes confined to the RPE (Panel B). Expression appears to be greater in the dorsal region of the retina (black arrow). Sections incubated with pre-blocked antibody demonstrated no signal (Panels C and D). R, retina; L, lens. Scale bar represents 10 μm.
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Figure 4: Immunofluorescent and immunohistochemical detection of RFC in developing mouse eye. Panel A demonstrates immunofluorescent signal for RFC present throughout the developing retina and lens of an E10.0 ICR mouse embryo. As development continues through E12.5, signal in the lens diminishes, while the signal in the retina becomes confined to the RPE (Panel B). Expression appears to be greater in the dorsal region of the retina (black arrow). Sections incubated with pre-blocked antibody demonstrated no signal (Panels C and D). R, retina; L, lens. Scale bar represents 10 μm.

Mentions: In addition to localizing RFC in numerous tissues of the developing embryo as shown in figure 3, we were particularly interested in its localization in the developing eye. Our laboratory has evaluated this protein in adult retina [3,5]. As shown in figure 4A RFC was present throughout the developing lens and retina at E10. As development continues through E12.5, RFC signal becomes undetectable in the lens, while signal in the retina becomes confined to the retinal pigment epithelium (RPE) (Figure 4B). Expression appeared to be greater in the dorsal RPE as compared to the ventral RPE (Figure 4B). Control experiments performed with either fluorescent secondary antibody (Figure 4C) or horse-radish peroxidase conjugated secondary antibody (Figure 4D) gave little background.


Reduced-folate carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart.

Maddox DM, Manlapat A, Roon P, Prasad P, Ganapathy V, Smith SB - BMC Dev. Biol. (2003)

Immunofluorescent and immunohistochemical detection of RFC in developing mouse eye. Panel A demonstrates immunofluorescent signal for RFC present throughout the developing retina and lens of an E10.0 ICR mouse embryo. As development continues through E12.5, signal in the lens diminishes, while the signal in the retina becomes confined to the RPE (Panel B). Expression appears to be greater in the dorsal region of the retina (black arrow). Sections incubated with pre-blocked antibody demonstrated no signal (Panels C and D). R, retina; L, lens. Scale bar represents 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC184426&req=5

Figure 4: Immunofluorescent and immunohistochemical detection of RFC in developing mouse eye. Panel A demonstrates immunofluorescent signal for RFC present throughout the developing retina and lens of an E10.0 ICR mouse embryo. As development continues through E12.5, signal in the lens diminishes, while the signal in the retina becomes confined to the RPE (Panel B). Expression appears to be greater in the dorsal region of the retina (black arrow). Sections incubated with pre-blocked antibody demonstrated no signal (Panels C and D). R, retina; L, lens. Scale bar represents 10 μm.
Mentions: In addition to localizing RFC in numerous tissues of the developing embryo as shown in figure 3, we were particularly interested in its localization in the developing eye. Our laboratory has evaluated this protein in adult retina [3,5]. As shown in figure 4A RFC was present throughout the developing lens and retina at E10. As development continues through E12.5, RFC signal becomes undetectable in the lens, while signal in the retina becomes confined to the retinal pigment epithelium (RPE) (Figure 4B). Expression appeared to be greater in the dorsal RPE as compared to the ventral RPE (Figure 4B). Control experiments performed with either fluorescent secondary antibody (Figure 4C) or horse-radish peroxidase conjugated secondary antibody (Figure 4D) gave little background.

Bottom Line: Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking.Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy.These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, USA. oxmandm@yahoo.com

ABSTRACT

Background: Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively.

Results: In the mouse, RFC transcripts and protein are expressed in the E10.0 placenta and yolk sac. In the E9.0 to E11.5 mouse embryo RFC is widely detectable, with intense signal localized to cell populations in the neural tube, craniofacial region, limb buds and heart. During early development, RFC is expressed throughout the eye, but by E12.5, RFC protein becomes localized to the retinal pigment epithelium (RPE).

Conclusions: Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy. The mechanism, however, by which folate supplementation ameliorates the occurrence of developmental defects is unclear. The present work demonstrates that RFC is present in placenta and yolk sac and provides the first evidence that it is expressed in the neural tube, craniofacial region, limb buds and heart during organogenesis. These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

Show MeSH
Related in: MedlinePlus